It grows fast alright!
I found this little corm rolling around in my 2ft guppy tank that had a little wirey root hanging out of it, so I stuffed it into the substrate, and after a little while - leaves! I was given this about three years ago and it sort of grew for a while and then disappeared, so was pleased that I had not killed it.
Since I upped the lighting, Co2 and ferts to get rid of the BBA it has grown into a monster, great big wavy leaves near the surface about 30mm across by 150ish long - dang, I think I need a taller tank now :-?